To define a user device. See corresponding section below about connstrings.

device.name="My Reader Name"
device.connstring="connstring"

This is the recommended method if the user has a not easily detectable device (ie. a serial one).
A sample is provided in the source code as libnfc.conf.sample

It is also possible to define devices using dedicated configuration files and put them into device search directory (/etc/nfc/devices.d under GNU/Linux).
Example for the OpenPCD2: create /etc/nfc/devices.d/openpcd2.conf with:

Note: to use I2C port on R-Pi, you have to load kernel modules i2c-bcm2708 and i2c-dev:
Edit /etc/modprobe.d/raspi-blacklist.conf and comment: #blacklist i2c-bcm2708
Edit /etc/modules and add a new line: i2c-dev

If you have an R-Pi revision 2.0, the I2C bus #1 is now routed to connector P1 (instead of the I2C bus #0 routed on same connector on initial board revision), so the configuration to use would probably be: